E-DRUG: Alert - Thimerosal in Vaccines

[srahmad@essential.org]

E-DRUG: Alert - Thimerosal in Vaccines
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July 09, 1999 / 48(26);563-565 

Notice to Readers:

Thimerosal in Vaccines: A Joint Statement of the American Academy of
Pediatrics and the U.S. Public Health Service 

The Food and Drug Administration (FDA) Modernization Act of 1997 called
for FDA to review and assess the risk of all mercury-containing food and
drugs. In line with this review, U.S. vaccine manufacturers responded to
a December 1998 and April 1999 FDA request to provide more detailed
information about the thimerosal content of their preparations that
include this compound as a preservative. Thimerosal has been used as an
additive to biologics and vaccines since the 1930s because it is very
effective in killing bacteria used in several vaccines and in preventing
bacterial contamination, particularly in opened multidose containers.
Some but not all of the vaccines recommended routinely for children in
the United States contain thimerosal.

There is a significant safety margin incorporated into all the
acceptable mercury exposure limits. Furthermore, there are no data or
evidence of any harm caused by the level of exposure that some children
may have encountered in following the existing immunization schedule.
Infants and children who have received thimerosal-containing vaccines do
not need to be tested for mercury exposure.

The recognition that some children could be exposed to a cumulative
level of mercury over the first 6 months of life that exceeds one of the
federal guidelines on methyl mercury now requires a weighing of two
different types of risks when vaccinating infants. On the one hand,
there is the known serious risk of diseases and deaths caused by failure
to immunize our infants against vaccine-preventable infectious diseases;
on the other, there is the unknown and probably much smaller risk, if
any, of neurodevelopmental effects posed by exposure to thimerosal. The
large risks of not vaccinating children far outweigh the unknown and
probably much smaller risk, if any, of cumulative exposure to
thimerosal-containing vaccines over the first 6 months of life.

Nevertheless, because any potential risk is of concern, the Public
Health Service (PHS), the American Academy of Pediatrics (AAP), and
vaccine manufacturers agree that thimerosal-containing vaccines should
be removed as soon as possible. Similar conclusions were reached this
year in a meeting attended by European regulatory agencies, European
vaccine manufacturers, and FDA, which examined the use of
thimerosal-containing vaccines produced or sold in European countries.

PHS and AAP are working collaboratively to assure that the replacement
of thimerosal-containing vaccines takes place as expeditiously as
possible while at the same time ensuring that our high vaccination
coverage levels and their associated low disease levels throughout our
entire childhood population are maintained.

The key actions being taken are

1.A formal request to manufacturers for a clear commitment and a plan to
eliminate or reduce as expeditiously as possible the mercury content of
their vaccines. 2.A review of pertinent data in a public workshop.
3.Expedited FDA review of manufacturers' supplements to their product
license applications to eliminate or reduce the mercury content of a
vaccine. 4.Provide information to clinicians and public health
professionals to enable them to communicate effectively with parents and
consumer groups. 5.Monitoring immunization practices, future
immunization coverage, and vaccine-preventable disease levels. 6.Studies
to better understand the risks and benefits of this safety assessment.

PHS and AAP continue to recommend that all children should be immunized
against the diseases indicated in the recommended immunization schedule.
Given that the risks of not vaccinating children far outweigh the
unknown and much smaller risk, if any, of exposure to
thimerosal-containing vaccines over the first 6 months of life,
clinicians and parents are encouraged to immunize all infants even if
the choice of individual vaccine products is limited for any reason.

While there is a margin of safety with existing vaccines containing
thimerosal, there are steps that can be taken to increase that margin
even further. Clinicians and parents can take advantage of the
flexibility within the existing schedule for infants born to hepatitis B
surface antigen (HBsAg)-negative women to postpone the first dose of
hepatitis B vaccine from birth until 2 to 6 months of age when the
infant is considerably larger. Preterm infants born to HBsAg-negative
mothers should similarly receive hepatitis B vaccine, but ideally not
until they reach term gestational age and a weight of at least 5.5 lbs
(2.5 kg). Because of the substantial risk of disease, there is no change
in the recommendations for infants of HBsAg-positive mothers or of
mothers whose status is not known. Also, in populations where HBsAg
screening of pregnant women is not routinely performed, vaccination of
all infants at birth should be maintained, as is currently recommended.
In addition to the key actions mentioned above, the PHS Advisory
Committee on Immunization Practices and the AAP Committee on Infectious
Diseases will be reviewing these issues and may make additional
statements.

Reported by: Public Health Service, US Dept of Health and Human
Services. American Academy of Pediatrics, Elk Grove Village, Illinois.

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